The present invention discloses compositions of matter and methods for producing stable silicone-water emulsions of volatile cyclic polysiloxanes without the need for milling or homogenization and which are particularly useful in cosmetic and medicinal applications.
The silicone-water emulsion composition of the present invention is particularly well-suited for serving as a vehicle for the application of epidermal enhancing agents. The expression "epidermal enhancing agents" refers to those compositions having properties generally considered as being beneficial when applied to portions of the body. For example, such agents include a wide range of cosmetics and medical and pharmaceutical compounds.
In the cosmetic category there are many types of products which can be beneficially applied to the skin in a silicone emulsion form. For example, such cosmetics would include cream eye shadows, foundations, blushes, lip gloss, mascara and eyeliner, cover-up-type compositions and wrinkle creams, moisturizers, acne cover-up depilatories and cuticle removers, etc.
Such emulsions can also be used for cleansing purposes and may take the form of shampoos, soaps, conditioners and moisturizers. Additionally, hair dyes may be applied in a silicone-water emulsion vehicle.
Additional cosmetic uses include the application of perfumes, colognes and sachets to the body. Among the particularly useful applications would be deodorants and antiperspirants.
Among the many medical uses of such an emulsion vehicle would be first aid uses such as burn ointments and the application of antiseptics. Furthermore, corn, wart and callous removing agents, for example, can be successfully applied to the skin in such a silicone-water emulsion vehicle.
Of course, the consistency of the silicone-water emulsion of the present invention can be varied through many degrees from a lotion-like consistency through cold cream-like pastes up to gel-type ointments or salves on the order of a petroleum jelly.
Silicones are synthetic polymers ordinarily commercially prepared from chlorosilane monomers and available in the form of fluids, resins and rubber gums. Of particular interest to the cosmetic industry are those polymers formulated into emulsions, greases, pastes, etc. In these formulations a wide variety of materials may be used in conjunction with the silicones.
Monomeric chlorosilanes are very reactive volatile materials which readily react with moisture to form silicones and byproduct hydrochloric acid. Thus, in the presence of moisture they are considered corrosive materials and may have hazardous properties and must be handled with care. However, after processing into silicone polymers these materials become bland and inert substances. Silicones may be further formulated with other materials to produce various end use compositions and often the physiological effect of the finished composition is determined by the nature of the nonsilicone component.
The toxocological properties of silicones have been widely studied and, as a group, polymeric silicone fluids and resins ordinarily have a very low order of toxicity. Considered from a practical viewpoint, the hazards they present are exceedingly minor. Silicone fluid polymers have been the subject of skin irritation and sensitization patch test studies and are typically shown to be safe. The low level of toxicity of silicone materials has even lead to the acceptance and successful use of silicone fluids in medical and dental applications.
Silicone fluids generally provide excellent protection against water-borne irritants such as harsh detergents and other household cleaning specialties. The chemical inertness and excellent water-repellency of silicone fluids are the major reasons for their effectiveness in preventing dermatitis. Silicones may also function as emollients, and provide pleasant non-stick "feel". Superior suntan lotions and creams can be prepared using silicones, since the silicone fluid is a carrier for the sunscreening agent and resists wash-off by either bathing or perspiration.
Emulsions containing volatile silicone cyclic polysiloxanes have been previously formulated by utilizing emulsifying agents such as dodecyl benzene sulfonic acid, however, these systems require milling or homogenization in order to emulsify the immiscible phases. It is possible to emulsify preparations of this type having only up to about 55% concentration of volatile cyclics and emulsions of this type are frequently utilized to carry out emulsion-type polymerization of cyclic such as octamethyltetrasiloxane.
The present invention provides a method which makes it possible to emulsify larger concentrations of cyclic polysiloxanes while at the same time eliminating the necessity of milling or homogenization. Additionally, the present invention provides stable emulsions of cyclic polysiloxanes such that these emulsions do not ordinarily "break" under normal storage and use conditions even when the concentration of volatile cyclic polysiloxane is 80% or more. This is a particularly useful property for consumer oriented products since these emulsions can therefore, ideally be utilized as vehicles for conveying epidermal enhancing agents onto the skin of a user in a beneficial manner.
Furthermore, the present invention offers a system for emulsifying volatile cyclic polysiloxanes which yield opaque to transparent materials, which can be readily formulated into many consumer products and particularly antiperspirants and deodorants, etc. Other potential uses for water based cyclic emulsions are skin care products such as hand lotions, skin fresheners, hair preparations and other grooming aids. As noted above, the method of the present invention provides a means for selectively varying the consistency of these emulsions depending upon the ultimate purposes of the product.
An additional advantage resides in the fact that these silicone-water emulsions are comprised of relatively volatile cyclic polysiloxane constituents such that an emulsion vehicle base will eventually evaporate from the skin and only the beneficial epidermal enhancing agent will be left thereon.
It is therefore an object of the present invention to provide a stable silicone-water emulsion formed from volatile cyclic polysiloxanes which is suitable for cosmetic and medicinal applications.
It is another object of the present invention to provide methods of preparing such silicone-water emulsions and methods for applying epidermal enhancing agents.